Check for existing executor (#3265)

* Check for existing executor

* Update release_notes.md

Author: jviau

release_notes.md

@@ -6,6 +6,8 @@
 
 ### Bug Fixes
 
+- Check if function invocation already has an executor before registering durable executor. (#3265)
+
 ### Breaking Changes
 
 ### Dependency Updates

src/Worker.Extensions.DurableTask/DurableTaskFunctionsMiddleware.cs

@@ -16,9 +16,9 @@ internal class DurableTaskFunctionsMiddleware(DurableFunctionExecutor invoker) :
     /// <inheritdoc />
     public Task Invoke(FunctionContext functionContext, FunctionExecutionDelegate next)
     {
-        if (functionContext.TryGetOrchestrationBinding(out _)
-            || functionContext.TryGetEntityBinding(out _)
-            || functionContext.TryGetActivityBinding(out _))
+        // If the function is a Durable Task function and there is no executor registered yet,
+        // register the Durable Function executor.
+        if (functionContext.Features.Get<IFunctionExecutor>() is null && functionContext.IsDurableTaskFunction())
         {
             functionContext.Features.Set<IFunctionExecutor>(invoker);
         }

src/Worker.Extensions.DurableTask/FunctionContextExtensions.cs

@@ -11,6 +11,16 @@ namespace Microsoft.Azure.Functions.Worker.Extensions.DurableTask;
 
 internal static class FunctionContextExtensions
 {
+    /// <summary>
+    /// Determines whether the function context represents a Durable Task function.
+    /// </summary>
+    /// <param name="context">The function context.</param>
+    /// <returns>True if function is a durable task trigger, false otherwise.</returns>
+    public static bool IsDurableTaskFunction(this FunctionContext context)
+        => context.TryGetOrchestrationBinding(out _)
+        || context.TryGetActivityBinding(out _)
+        || context.TryGetEntityBinding(out _);
+
     /// <summary>
     /// Tries to get the orchestration trigger binding from the function context.
     /// </summary>